The surface plasmon resonance instrument (BIAcore 2000) requested in this proposal will be used to measure the kinetic and equilibrium constants of biomolecular interactions in a variety of systems. The systems involve protein/protein interactions (T-cell receptor/peptide MHC or super-antigen ligands; engineered single chain antibodies/T-cell receptor; chemotaxis receptor/signal transducing proteins; homotropic interactions of the cell adhesion protein E-cadherin; T-cell receptor CD4/CD48); protein/nucleic acid interactions (estrogen receptor/DNA recognition sequences; vigilin/RNA recognition sequences); and protein/lipid interactions (plasma proteins/lipoproteins; apolipoproteins/phospholipid surfaces). The six investigators contributing to this proposal come from the Departments of Biochemistry and Chemical Engineering of the University of Illinois and are members of the Biotechnology Center. The surface plasmon resonance instrument will be the first such instrument on this campus. It will be located in the Immunological Resource Center of the Biotechnology Center which will assume the responsibility for the maintenance, and day-to-day administration of this instrument.